The purpose of the Exposure Assessment Core is to provide a centralized resource for the conduction of exposure assessment activities related to children's asthma research. The objectives are to provide, input into research design, field sampling equipment and support, and analytical services. Support of an Exposure Assessment Core Facility is justified based on the importance of exposure related activities associated with the epidemiology project, the intervention study, basic science project, the new investigator project, and the community outreach core. In addition, the Core will interact with the Data Management Core to provide exposure assessment data for integration into epidemiologic analyses.